A negative electrode, a preparation method thereof, a solid-state battery, and an electric device

Abstract

This invention relates to the field of lithium battery materials technology, and in particular to a negative electrode and its preparation method, a solid-state battery, and an electrical device. A negative electrode includes a lithium metal layer and a modification layer on at least one surface of the lithium metal layer; the modification layer includes an organic compound and a non-metallic lithium compound, wherein the organic compound contains halogens and ether groups, and the arithmetic mean roughness of the modification layer is 0.05–1.6 nm. The negative electrode of this invention, by modifying the lithium metal layer with specific organic compounds and non-metallic lithium compounds, can reduce the direct contact between the solid electrolyte and the lithium metal, lower the interfacial impedance, and facilitate lithium-ion deposition, thereby improving the battery's utilization rate and cycle life.

Description

Technical Field

[0001] This invention relates to the field of lithium battery materials technology, and in particular to a negative electrode and its preparation method, a solid-state battery, and an electrical device. Background Technology

[0002] Lithium metal anodes have long been considered the preferred anode for improving the energy density of lithium batteries because they possess a very low electrochemical potential (-3.04 V vs. SHE) and a relatively low density (0.53 g·cm³). -1 ) and a very high theoretical capacity (3860 mAh·g) -1 However, lithium metal is very reactive and readily reacts with other substances, and it easily forms lithium dendrites on its surface. During battery cycling, lithium dendrites can easily puncture the electrolyte, leading to internal short circuits and serious safety issues.

[0003] Using high-strength solid-state electrolytes to fabricate all-solid-state batteries holds promise for enabling the application of lithium metal anodes and improving battery energy density. However, most solid-state electrolytes are unstable with lithium metal, forming a high-resistivity interface layer during battery cycling. Furthermore, the poor contact between solid-state electrolytes and lithium metal leads to uneven current distribution, promoting lithium dendrite growth. These dendrites can penetrate the gaps in the solid-state electrolyte and reach the positive electrode, causing a short circuit in the battery.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] One objective of this invention is to provide a negative electrode to solve the technical problems existing in the prior art, such as poor interfacial chemical stability and high interfacial impedance between solid electrolyte and lithium metal negative electrode.

[0006] To achieve the above-mentioned objectives of this invention, the following technical solution is adopted:

[0007] A negative electrode includes a lithium metal layer and a modification layer on at least one surface of the lithium metal layer; the modification layer includes an organic compound and a non-metallic lithium compound, the organic compound comprising halogens and ether groups, and the arithmetic mean roughness of the modification layer is 0.05 to 1.6 nm.

[0008] Furthermore, based on the mass of the modified layer, the content of the organic matter is 0.1% to 5%.

[0009] Furthermore, the porosity of the modified layer is 2% to 10%.

[0010] Furthermore, the thickness of the modified layer is 0.05–2 μm.

[0011] Furthermore, in the modified layer, the morphology of the non-metallic lithium compound includes any one or more of the following: sheet-like, granular, and linear forms.

[0012] Furthermore, the size of the non-metallic lithium compound is 5–500 nm.

[0013] Furthermore, the non-metallic lithium compound includes any one or more of LiF, LiCl, and LiBr.

[0014] Another object of the present invention is to provide a method for preparing a negative electrode, comprising the following steps:

[0015] The negative electrode is obtained by contacting a lithium metal sheet with a gaseous halogen-containing ether compound.

[0016] Another object of the present invention is to provide a solid-state battery, comprising a solid electrolyte and any of the above-described negative electrodes, wherein the interfacial impedance between the solid electrolyte and the negative electrode is 50 to 160 Ω.

[0017] Another object of the present invention is to provide an electrical device comprising any of the solid-state batteries described above, wherein the solid-state battery serves as the power supply for the electrical device.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] (1) The negative electrode of the present invention is modified with specific organic and non-metallic lithium compounds on the lithium metal layer, which can reduce the direct contact between the solid electrolyte and the lithium metal, reduce the interface impedance, and facilitate the deposition of lithium ions, thereby improving the utilization rate and cycle life of the battery.

[0020] (2) The method for preparing the negative electrode of the present invention is simple to operate, mild under mild conditions, and easy to prepare on a large scale;

[0021] (3) The negative electrode of the present invention has good chemical stability and low interface impedance at the interface with the solid electrolyte. It can be used in solid batteries and as a power supply for electrical equipment. It has good battery utilization and cycle life. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a graph showing the F element distribution on the surface of the modified layer of the negative electrode obtained in Example 1 of the present invention.

[0024] Figure 2 The F element distribution on the surface of the modified layer of the negative electrode prepared in Comparative Example 3;

[0025] Figure 3 This is a cycle performance test diagram of the battery obtained in Example 1 of the present invention. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0027] The present invention provides a negative electrode comprising a lithium metal layer and a modification layer on at least one surface of the lithium metal layer; the modification layer comprises an organic compound and a non-metallic lithium compound, the organic compound comprising halogens and ether groups, and the arithmetic mean roughness of the modification layer is 0.05 to 1.6 nm.

[0028] In the negative electrode of this invention, organic compounds and non-metallic lithium compounds with specific groups are modified on the lithium metal layer. This reduces the direct contact between the solid electrolyte and the lithium metal, lowers the interfacial impedance, and further improves the deposition / dissolution behavior of lithium, resulting in better battery safety and cycle performance. Specifically, the non-metallic lithium compounds have excellent lithium-ion transport performance, reduce the internal resistance of the electrode, and can also guide the insertion / extraction of lithium ions, resulting in a uniform electric field distribution and preventing the growth of lithium dendrites. In addition, the ether groups contained in the organic compounds in the modification layer improve the wettability of the electrode to the electrolyte. Halogens can passivate lithium metal and effectively suppress side reactions between the electrode and the electrolyte. Furthermore, the arithmetic mean roughness of the modification layer is 0.05–1.6 nm, indicating that the modification layer is tightly and uniformly bonded to the lithium metal layer. This further effectively blocks the contact between the lithium metal negative electrode and the solid electrolyte, while reducing the probability of tip discharge during lithium ion insertion / extraction, reducing the growth of lithium dendrites, and improving the cycle stability of the battery.

[0029] In some embodiments, the organic compound includes at least one selected from 1,1,2,2-tetrafluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, chloromethyl methyl ether, chloromethyl ethyl ether, and 2-bromoethyl methyl ether.

[0030] In some specific embodiments of the present invention, the content of the organic matter is 0.1% to 5% based on the mass of the modified layer.

[0031] In different embodiments, based on the quality of the modified layer, the content of the organic matter can be, for example, one or any two of the following ranges: 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%. When the content of the organic matter in the modified layer meets the above requirements, it can ensure that the electrode has better wetting performance while also ensuring uniform deposition of lithium ions and avoiding the growth of lithium dendrites.

[0032] In some specific embodiments of the present invention, the porosity of the modified layer is 2% to 10%.

[0033] In various embodiments, the porosity of the modified layer can be exemplary, ranging from one or any two of 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%. Within these porosity ranges, it is beneficial to improve the wetting performance of the electrode and reduce the internal resistance of the battery.

[0034] The modified layer of the present invention has high density and can effectively block the contact between the lithium metal anode and the solid electrolyte.

[0035] In some specific embodiments of the present invention, the thickness of the modification layer is 0.05 to 2 μm.

[0036] In different embodiments, the thickness of the modification layer can be, for example, one or any two of the following ranges: 0.05 μm, 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, and 2 μm. An appropriate thickness of the modification layer can fully exert its effect on improving lithium deposition, effectively enhancing battery safety performance; simultaneously, it can also give the battery lower impedance, improve cycle performance, and facilitate achieving higher energy density. The thickness of the modification layer in this invention, within the above range, ensures both its barrier effect on the lithium metal anode and the solid electrolyte, guaranteeing safety performance, and also ensures battery utilization, improves cycle performance, and increases battery energy density.

[0037] In some specific embodiments of the present invention, the non-metallic lithium compound in the modified layer includes one or more of the following morphologies: sheet-like, granular, and linear. These morphologies of the non-metallic lithium compound facilitate uniform distribution, while simultaneously reducing the lithium-ion transport path and increasing the lithium-ion transport rate.

[0038] To further improve the uniform dispersion of non-metallic lithium compounds and increase the lithium ion transport rate, in some specific embodiments of the present invention, the size of the non-metallic lithium compounds is 5 to 500 nm.

[0039] In different embodiments, the size of the non-metallic lithium compound in the modification layer may, for example, be one or any two of the following ranges: 5nm, 10nm, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, and 500nm.

[0040] In some specific embodiments of the present invention, the non-metallic lithium compound includes any one or more of LiF, LiCl, and LiBr.

[0041] The non-metallic lithium compounds, especially fluorine, in the modification layer can passivate lithium metal, effectively suppressing side reactions between the electrode and the electrolyte, thereby improving the cycle stability of the lithium metal anode. Furthermore, the halide interface formed by the non-metallic lithium compounds possesses high interfacial energy and a low lithium-ion interfacial diffusion barrier, ensuring more uniform lithium metal deposition and effectively suppressing lithium dendrite nucleation and growth. In addition, the halide interface also exhibits good mechanical stability, effectively preventing interface damage during lithium deposition and providing support for the long-term stable cycling of the lithium metal anode.

[0042] Another object of the present invention is to provide a method for preparing a negative electrode, comprising the following steps:

[0043] The negative electrode is obtained by contacting a lithium metal sheet with a gaseous halogen-containing ether compound.

[0044] In this embodiment, the halogen-containing ether compound includes at least one selected from 1,1,2,2-tetrafluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, chloromethyl methyl ether, chloromethyl ethyl ether, and 2-bromoethyl methyl ether. The reaction of the halogen-containing ether compound with lithium metal results in the formation of a modification layer on the lithium metal surface containing a non-metallic lithium compound, as well as halogen-containing and ether groups.

[0045] In some specific embodiments of the present invention, the contact time is 0.5 to 24 hours.

[0046] In different implementations, the contact time may be, for example, a range of one or any two of the following: 0.5h, 1h, 2h, 4h, 8h, 12h, 16h, 20h, and 24h.

[0047] In some specific embodiments of the present invention, the preparation method includes the following steps:

[0048] Halogenated ether compounds can be heated to yield gaseous halogenated ether compounds.

[0049] The lithium metal sheet is placed in a system of gaseous halogen-containing ether compounds, and the lithium metal sheet is brought into contact with the gaseous halogen-containing ether compounds to produce a negative electrode after the reaction.

[0050] This can be achieved by heating the ether compound to vaporize it. The heating temperature can be adjusted according to the vaporization temperature of the halogen-containing ether compound to ensure that a gaseous halogen-containing ether compound is obtained. For example, the heating temperature can be 80–178°C.

[0051] Heating allows vaporized ether compounds to react with the lithium metal substrate, which can improve the adhesion between the modified layer and the substrate, ensuring a tighter contact between the modified layer and the lithium metal substrate and making the structure less susceptible to damage.

[0052] Another object of the present invention is to provide a solid-state battery, comprising a solid electrolyte and any of the above-described negative electrodes, wherein the interfacial impedance between the solid electrolyte and the negative electrode is 50 to 160 Ω.

[0053] The solid-state battery of the present invention can achieve high safety performance and cycle performance because it uses the negative electrode of the present invention.

[0054] In some specific embodiments of the present invention, the solid-state battery further includes: a solid-state electrolyte; the solid-state electrolyte includes any one of inorganic solid-state electrolyte and polymer solid-state electrolyte.

[0055] In some specific embodiments of the present invention, the solid-state lithium battery includes a sulfide solid-state lithium battery.

[0056] Another object of the present invention is to provide an electrical device comprising any of the solid-state batteries described above, wherein the solid-state battery serves as the power supply for the electrical device.

[0057] The electrical device of the present invention includes the above-described solid-state battery, and therefore has at least the same advantages as the solid-state battery.

[0058] Example 1

[0059] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0060] (1) Polish the lithium metal sheet;

[0061] (2) Take 50% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0062] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 140°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0063] Example 2

[0064] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0065] (1) Polish the lithium metal sheet;

[0066] (2) Take 5% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0067] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 140°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0068] Example 3

[0069] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0070] (1) Polish the lithium metal sheet;

[0071] (2) Take 10% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0072] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 140°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0073] Example 4

[0074] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0075] (1) Polish the lithium metal sheet;

[0076] (2) Take 25% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0077] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 140°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0078] Example 5

[0079] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0080] (1) Polish the lithium metal sheet;

[0081] (2) Take 40% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0082] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 140°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0083] Example 6

[0084] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0085] (1) Polish the lithium metal sheet;

[0086] (2) Take 55% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0087] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 140°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0088] Example 7

[0089] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0090] (1) Polish the lithium metal sheet;

[0091] (2) Take 65% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0092] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 140°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0093] Example 8

[0094] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0095] (1) Polish the lithium metal sheet;

[0096] (2) Take 70% 1,1,2,2-tetrafluoroethyl ether and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0097] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 140°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0098] Example 9

[0099] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0100] (1) Polish the lithium metal sheet;

[0101] (2) Take 1,1,2,2-tetrafluoroethyl ether with a concentration of 80% and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0102] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 140°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0103] Example 10

[0104] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0105] (1) Polish the lithium metal sheet;

[0106] (2) Take 50% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0107] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 70°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0108] Example 11

[0109] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0110] (1) Polish the lithium metal sheet;

[0111] (2) Take 50% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0112] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 80°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0113] Example 12

[0114] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0115] (1) Polish the lithium metal sheet;

[0116] (2) Take 50% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0117] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 120°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0118] Example 13

[0119] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0120] (1) Polish the lithium metal sheet;

[0121] (2) Take 50% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0122] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 180°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0123] Example 14

[0124] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0125] (1) Polish the lithium metal sheet;

[0126] (2) Take 50% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 1,1,2,2-tetrafluoroethyl ethyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0127] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 190°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0128] Example 15

[0129] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0130] (1) Polish the lithium metal sheet;

[0131] (2) Take 50% 2-bromoethyl methyl ether and add it to a 50 mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the 2-bromoethyl methyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0132] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 170°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0133] Example 16

[0134] This embodiment provides a negative electrode and its preparation method, wherein the preparation method of the negative electrode includes the following steps:

[0135] (1) Polish the lithium metal sheet;

[0136] (2) Take 50% chloromethyl methyl ether and add it to a 50mL sealable heat-resistant container. Place the lithium metal sheet treated in step (1) above the chloromethyl methyl ether, ensuring that the lithium metal sheet does not come into contact with the ether liquid. Then seal the heat-resistant container.

[0137] (3) Place the sealed heat-resistant container from step (2) in an oven and heat it at 170°C for 10 hours. Then cool it to room temperature and remove the lithium metal sheet to obtain a surface-modified lithium metal anode.

[0138] Comparative Example 1

[0139] The preparation method is the same as in Example 1, except that 1,1,2,2-tetrafluoroethyl ether in step (1) is replaced with tetrafluoromethane.

[0140] Comparative Example 2

[0141] The preparation method is the same as in Example 1, except that only the lithium metal sheet polishing step is included.

[0142] Comparative Example 3

[0143] (1) Polish the lithium metal sheet;

[0144] (2) Take 50% 1,1,2,2-tetrafluoroethyl ethyl ether and add it to a 50 mL sealable heat-resistant container. Immerse the lithium metal sheet treated in step (1) into the above-prepared solution and let it stand for 10 hours.

[0145] (3) After being removed and dried, a surface-modified lithium metal anode is obtained.

[0146] The prepared negative electrode exhibits the parameter characteristics shown in Table 1. The negative electrodes from Examples 1-16 and Comparative Examples 1-3 were assembled into solid-state batteries, and the solid-state batteries were subjected to cycle performance and internal resistance tests. The positive electrode of the solid-state battery is lithium cobalt oxide, and the solid electrolyte is Li. 10 GeP2S 12 .

[0147] The cycle performance and rate performance testing methods are as follows: At room temperature, the battery is left to rest for 5 minutes, then charged at a constant current rate of 0.1C to 4.2V, followed by constant voltage charging until the current is less than or equal to 0.05C. After resting for 5 minutes, it is discharged at a constant current rate of 0.1C to 3.0V. This constitutes one charge-discharge cycle, and the discharge capacity of this cycle is recorded as the charge-discharge capacity of the lithium-ion secondary battery in the first cycle. The battery is cycled 100 times using the above method, and the charge-discharge capacity of each cycle is recorded. The battery capacity retention rate (%) = discharge capacity of the 100th cycle / discharge capacity of the 1st cycle × 100%. Figure 3 The battery cycle performance test graph of Example 1 is shown.

[0148] The method for testing internal resistance is as follows: the internal resistance of the battery can be obtained using a battery internal resistance tester.

[0149] Roughness: Measured using AFM (Atomic Force Microscopy).

[0150] Table 1

[0151]

[0152]

[0153]

[0154] The test results above show that the negative electrode of the present invention, when used in a battery, can significantly improve the battery's cycle performance and reduce its internal resistance, thereby enhancing its rate performance. Furthermore, data from Examples 1-16 and Comparative Example 3 indicate that the modified layer obtained using the steam method is denser and has lower surface roughness than the modified layer obtained using the traditional immersion method. This effectively reduces tip discharge during lithium ion insertion / extraction at the negative electrode interface, thereby reducing lithium dendrite growth and improving battery cycle performance.

[0155] In addition, Figure 1 , 2 The distribution maps of the F elements in the modified layer in Example 1 and Comparative Example 3, obtained based on EDS mapping tests, are shown respectively. Figure 1 , 2As can be seen, the distribution of F element in the modified layer is more uniform in Example 1, which reflects that the modified layer of fluorine-containing compound obtained in the example is denser and the fluoride distribution is more uniform. Based on this, it can effectively block the contact between the lithium metal anode and the solid electrolyte, and make the lithium ion insertion / extraction process more uniform.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A negative electrode, characterized in that, The device includes a lithium metal layer and a modification layer on at least one surface of the lithium metal layer; the modification layer includes an organic compound and a non-metallic lithium compound, the organic compound comprising halogens and ether groups, and the arithmetic mean roughness of the modification layer is 0.05~1.6 nm. The thickness of the modified layer is 0.05~1.8μm; Based on the mass of the modified layer, the content of the organic matter is 0.5% to 4.5%; The non-metallic lithium compounds include any one or more of LiF, LiCl, and LiBr.

2. The negative electrode according to claim 1, characterized in that, The porosity of the modified layer is 2% to 10%.

3. The negative electrode according to claim 1, characterized in that, In the modified layer, the morphology of the non-metallic lithium compound includes any one or more of the following: flake, granular, and linear.

4. The negative electrode according to claim 1, characterized in that, The particle size of the non-metallic lithium compounds is 5~500 nm.

5. The method for preparing the negative electrode according to any one of claims 1 to 4, characterized in that, Includes the following steps: The negative electrode is obtained by contacting a lithium metal sheet with a gaseous halogen-containing ether compound.

6. A solid-state battery, characterized in that, It includes a solid electrolyte and a negative electrode as described in any one of claims 1 to 4, wherein the interfacial impedance between the solid electrolyte and the negative electrode is 50 to 160 Ω.

7. An electrical appliance, characterized in that, The device includes the solid-state battery as described in claim 6, wherein the solid-state battery serves as the power supply for the electrical device.

Images